Analysis Process for Different Polymere Electrolyte Fuel Cell Stacks to Derive a Control Stratgy Based Impedance Data

To further the development of polymer electrolyte membrane (PEM) fuel cells control strategies must be developed and optimized. In this study, an analysis process to derive a control strategy based on impedance data is developed and investigated. For this purpose an air cooled stack consisting of 12 cells and developed at Fraunhofer ISE was investigated. Impedance spectra were measured at different operating conditions to identify relevant frequencies at which an online control algorithm should be developed. A comparison of the impedance data between the analyzed stack and commercially available stacks of both air cooled and liquid cooled architectures suggest that the usable frequency ranges are independent of the stack. Hence, the presented analysis process is not limited to a specific stack design and yields a measure for the fuel cell's state of health that does not need information of a complete spectrum, but rather uses impedance data at a few discrete frequencies as control input.